To decrease its call volume using an Experience site, NTO can use standard out-of-the-box functionality such as:
Create an FAQ Knowledge article. A Knowledge article is a document that provides information or a solution to a common issue or question. NTO can create an FAQ Knowledge article that answers the most frequently asked questions by its customers and publish it on its site.
Deploy a chatbot to address common questions. A chatbot is an automated conversational agent that can interact with customers using natural language. NTO can deploy a chatbot on its site that can answer common questions, provide information, or escalate issues to agents.
Enable Chatter Questions to encourage peer-to-self-service. Chatter Questions is a feature that allows customers to post questions on your site and get answers from other customers or experts. NTO can enable Chatter Questions on its site to encourage peer-to-self-service and reduce the need for support calls.

This option allows UC to customize the self-registration process and create person accounts programmatically using Apex code. The standard self-registration configuration does not support person accounts and requires an existing business account to associate the new users with. Restricting the account record type access for the Site Guest User does not affect the self-registration process and may cause errors.

Audience targeting allows you to display different content to different audiences based on criteria such as profile, location, domain, or user. However, there are some limitations of audience targeting, such as:
You can't assign audiences to the components in the template header and footer sections. These sections are shared across all pages in your site and can't be customized for different audiences.
You can't assign record-based criteria to a component or branding set. Record-based criteria are only available for page variations and navigation menu items.

Deal Registration allows UMS to enable its partners to register deals and work with UMS on sales opportunities. UMS can also set up approval processes and validation rules for deal registration and track the deal status and revenue. Lead Distribution allows UMS to assign leads to partners based on predefined criteria, such as location, product, or industry. UMS can also monitor the lead conversion rate and partner performance. Market Development Fund allows UMS to allocate funds to partners for marketing activities, such as events, campaigns, or webinars. UMS can also create budgets, approval workflows, and reports for market development fund.

Three features that CK should use to organize content on its site are Content Topics, Content Graph, and Navigation Tree. Content Topics are keywords or phrases that help users find and organize content in Experience Cloud sites. Content Topics can be assigned to any content, such as articles, posts, or files.
Content Graph is a feature that analyzes the relationships between content and topics and suggests relevant content to users based on their interests and preferences. NavigationTree is acomponent that allows you to create a hierarchical structure of topics and subtopics that users can browse through to find content.